Conventionally, electrical tools that drive a screwdriver or a drill bit can only rotates. For the reason that the screw driver or the drill bit may get stuck in the material of the work pieces the electrical tool is made to be switchable between simple rotation and rotation with vibration which allows the tool to work more effective and efficiently by combining rotation and axial vibration.
The prior art electrical tool capable of rotating with vibration comprises an impress ring of a steel ball, a spring, and a stop ring sequentially fit over a canister. The spring is seated between the stop ring and the impress ring of the steel ball. Plural teeth are formed on the top of the canister. Springs, a switch set, a vibration block and a vibration set are sequentially fit over an output shaft. Teeth are formed on both the vibration block and the vibration set and are engageable with each others The stop ring is fixed on the knob. With control juts formed on the back end of the electrical tool pushing the switch set, the teeth of the vibration block and the teeth of the vibration set are controlled to engage or to separate. When the teeth engage each other, the vibration set is fixed and the vibration block rotates with the rotation of the output shaft. This causes the output shaft to rotate with axial vibration. When the teeth of the vibration block and the teeth of the vibration set separate, the output shaft can only rotate without vibration.
The above prior art structure of the electrical tools, which can be switched between simple rotation and rotation with vibration, utilizes the jut eccentrically formed on the stop ring to push the switch set. When the stop ring rotates, the spring set on the jut drives the switch set to move axially. Further, it controls the vibration block and the vibration set to engage each other, which causes the axial vibration. Therefore, when the stop ring rotates, the single jut works in the eccentric position of the switch set and the rotation is only allowed in one direction. The movement of the switch set in the axial direction is unstable and the precision of switching operation is poor. Thus, the present invention intends to improve the prior art design of the electrical tool which is capable of switching between simple rotation and rotation with vibration.